Vitreous enamel organosol



Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE VITREOUS ENAMEL ORGANOSOL No Drawing. Application December 31, 1935,

Serial No. 56,909 1 15 Claims.

The present invention relates to the production of vitreous enamel organosols which may be applied to metal bases by spraying, dipping, etc.

One object of my invention has to do with a 5 vitreous enamel organosol, the liquid phase of which comprises an organic boron compound.

Another object of my invention relates to the production of vitreous enamel organosols, the solid phase of which is dispersed in an aliphatic boron compound.

A third object of my invention has to do with a vitreous enamel organosol comprising a finely divided vitreous enamel frit dispersed in an aromatic boron compound.

A fourth object of this invention relates to the production of vitreous enamel organosols, the solid phase of which is dispersed in a boric acid ester.

A fifth object of my invention has to do with )2 the addition of protective colloids or inert diluents to the organosols set forth above, to promote floating of the solid phase in the liquid phase of the organosol.

Other objects of my invention will become apparent to those skilledin the art after a study of the following specifications,

Vitreous enamel, in reality a glass composition of a relatively low fusibility, is principally composed of silicates, borates, fluorides, etc. In producing such vitreous enamel, so-called glassforming substances are mixed with auxiliary substances in certain definite proportions to form a composition which, subsequently, is fused and quenched in water. The product, obtained after quenchingiscalled in the art enamel frit. This frit is ground in'w'ater, containing clay, to a fine composition, the so-called vitreous enamel slip which may be applied to metal bases by spraying or dipping.

The aforementioned glass forming substances are the following:

1. Raw materials for introducing acid oxides (silicon, boron).

2. Raw materials for introducing basic oxides 45 (soda, potash, lime, magnesia, lead oxide, etc.). 3. Raw materials for introducing acid and basic oxides (borax, fluorspar, kaolin, etc.).

The auxiliary substances, set forth above, are the following:

1. oxidizing agents (sodium nitrate, etc.). 2. Adhering oxides (cobalt, nickel, manganese oxides, etc.).

3. Opacifiers (phosphates, fluorides, pigments, etc.).

Heretofore, vitreous enamel slips havebeen prepared bymilling enamel frit with water containing about 7% clay to a fine consistency, said clay being added to float the frit particles by hydration. This method, however, is unsatisfactory for the reason that frit particles give off a number of alkaline compounds in the presence of water.

These alkaline compounds thin out the clay of the enamel s1ips,,and as a result the clay loses its floating property. Thus, the frit and clay particles settle inv very short periods of time, and

it becomes impossible to maintain a proper consistency of theenamel. slip. A number of methods have: been introduced to maintain or restore the consistency of enamel slips, i. e., enamel hydrosols.

Acid salts, for example, magnesium sulphate, are.

added to enamel slips to neutralize the alkaline compounds generated by the frit particles. Although the colloidal magnesium hydroxide, produced-by chemical interaction of magnesium sulphate and said alkaline compounds, somewhat assists in floating enamel particles, this so-called setting up of aqueous enamel slips has proven unsatisfactory. Another method consists in adding buffer solutions to vitreous enamel slips. toneutralize the alkalis, originating from the frit particles, to maintain the original optimum pH values of such slips. [Although this method, set forth in my application, Ser. No. 5i8,712,-filed July 3, 1931, gives satisfactory results, I have found that it is extremely diflicult to permanently set up a stainless enamel frit ground in water. In addition, such enamel hydrosols form rust on metal bases to Which they are applied before firing, and as a result of such rusting so-called mottled enamel coatings are obtained. Experimentation with enamel hydrosols proved that such rusting of metal bases is caused by thealkaline compounds dissociating in the presence of water to active anions and cations. To completely overcome this deficiency, it is necessary to disperse frit particles in nonor very little conducting, organic liquids. In this manner the troublesome OH groups of alkalis are eliminated, i. e., inactivated.

I am well aware that it has, heretofore, been proposed to suspend special types of enamels in oils, and to fuse such oil-enamel suspensions on metal bases, such asv silver, gold, etc. However, I have found this method to be unsatisfactory for enameling iron, steel, etc., for the reason that oils per se burn out with the formation of gases and finely divided carbon. The gases and carbon escaping from the enamel coating upon fusing tend to cause the formation of uneven enamel coatings with so-called pin-holes. Unexpecteddispersing enamel frit in such organic liquids which do not only prevent the formation of active hydroXyl groups but which, in addition, produce upon firing such residual compounds which .promote the adherence of fused enamel frit to metal bases, while blending therewith.

In accordance with my present invention, I.

disperse vitreous enamel frit in organic boron of dispersing enamel frit-in liquid boron compounds, I may suspend it in a solid, anhydrous,

organic boron compound dissolved and/or dispersed in an anhydrous, liquid, organic compound, a so-called inert diluent. enamel frit is milled with such organic boron compounds or dispersed therein inthe'totalab-f sence of water, thealkaline compounds, generated by the'frit, do not form electrolytes with the boron'compounds, the latter being practically non-conducting in anhydrous form. When such an organosol, consisting @of finely divided frit and organic boron compounds ,'is applied to iron or steel plates,:for example, these plates are not corroded. Therefore, the enamel coatings do not become mottled on firing and the'formation of a pure, white coating, for example, is assured. .In addition, the boron oxide formed upon firing the enamel slip onto the metal base, blends with] the enamel composition and promotes the adherencethereof to said metal base. ,j

I have found that all such organic silicon compounds may be used which are liquid and stableat ordinary room temperatures, or which coholsfe'sters, mineral andvegetable oils, etc.

Thus, I may use aliphatic and aromatic, i. e., carbocyclic and heterocyclic,.boroncompounds havingthe aforementioned properties. The followingtable depicts a number of organic boron derivatives which may be used in the production of vitreous enamel organosols ,7 Table 7 Boiling or- Compound Formula melting point indegree C Trimethyl borate Triethyl borate. Monoethyl borate. 2 Methyl-diethyl bora Tripropyl borate B(O. O )3 Triisopropyl borate BOIl(C3H7)3 140 'lriisobutyl borate B(O. 041103; l 160-170 Triisoamyl borate B(OC5H11)a 4 -Monoisoamyl borate BOz(C Hn) Undeter- V mined Diethyl-isoamyl borate 1304051111) (02m): 173-175 Ethyl-diisoamyl borate- BO3(O5H ;g(C H 210-215 Trioctyl borate BOz(CgH11 a Undetermined Monocetyl borate 13016161133) '58 Iriallyl borate -B(OCzHn)3 168-175 Trigthylene monobor- B(O. CHLCHZOHM" 161. 7 a o. i .Glycerine borate O3H5BO3 Undeter mined Ethylbonc acid; (CzH5)B(OH)2.'- D ethylaminochlorobor- (CzH5)2N. BC12 me. Phenylboric acid PhBOz 204 Boron .trisalicylato B(O. G H4OO2H)3 230 'lriboro resorcylic acid B(OzHz. (hHgCOzHh. 220

boric acid, boric acidesters of aromatic alcohols,

etc. In other'words, I may employ any organic When. an I Y added thereto.

boron compound which is anhydrous and stable at ordinary room temperature.

In recent years, vitreous enamel has been produced which resists the action of acids such as contained in lemon juice, for example. These acid-resistant enamels, the so-called stainless enamels, are low in, or entirely free from, alumina and high in silica content (up to 50% silica).

{Ihese stainless enamels will rapidly settle their solid phases in water due to large amounts of compounds which are liquid, anhydrous 'and stable at ordinary room temperatures. Instead alkaline compounds dissolving from the frit particles. Finally, the clay-enamel suspension becomes thinnerand thinner, and the solid phases settle to a. dense, hardmass. In addition, when ;such slips are applied to iron or steel bases, they rust these metals in very short periods of time, and it becomes impossible to'produce a clear,

single coat on iron or steel, etc. In order to produce a clear, white coating of enamel, for example, on iron or steel, itis necessary to fuse several layers of white enamel onto these metals to camouflage the rust-spots of the first enamel coating.

I am well aware that attempts have, heretofore, been made" to overcome the tendency of metals to overcome the mottling effect of stainless enamel. Yet, I have found that it is possible to form a single, white enamel coating on iron and steel provided the frit particles are not suspended in aqueous media but in anhydrous, organic boron compounds. Although it is possible to disperse the frit in suchboron compounds without any further additions thereto, I have found that the settling of the frit= particles may be prevented for relatively long periods of time with the assistance of suitable protective colloids. Naturally, it is impossible to use such protective colloids which act in a hydrated form, such as gelatine, agar, alginates, etc., but I have found that oil-soluble soaps, such as barium, strontium,

magnesium soaps etc., produced by causing a metal salt to react with fatty acids, will effectively prevent the floating of stainless enamels in organic boron compounds. In addition, soaps formed by chemical interaction of naphthenic can be used which are somewhat soluble in organic boron compounds or in organic diluents The use of such protective'colloids is naturally not limited to stainless enamel 1 frits since any enamel frit will remain in suspension for longerperiods of time in the presence of such colloids.

L The amounts of vitreous enamed frit to be milled with or suspended in a given amount of a liquid, organic boron compound may be varied at will to form more or less viscous organosols to which clay. protective colloids, etc., maybe added. Solid organic boron derivatives may bedissolved in liquid ones, or they may be dissolved and/or emulsified with other stable, organic li'q- "uids; such as hydrocarbons, vegetable, mineral oils, etc., theseliquids being called inert diluents. The finished organosols may be applied to metal bases, etc., by spraying or dipping. Before firing, the moist enamel layer is air-dried. This drying is preferably carried out in chambers which allow recovery of the vapors of the boron derivatives by condensation, absorption, etc.

I desire to point out that all ingredients of my vitreous enamel organosols must be anhydrous, i. e., free from water, to prevent the formation of metal-corroding ions. Modifications of my process will readily be recognized by those skilled in the art, and I desire to include all such modifications falling within the scope of the appended caims.

I claim:

1. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid organic boron compound, said compound being anhydrous and stable at ordinary room temperatures.

2. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aliphatic boron compound, said compound being anhydrous and stable at ordinary room temperatures.

3. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aromatic boron compound, said compound being anhydrous and stable at ordinary room temperatures.

4. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid boric acid ester, said ester being anhydrous and stable at ordinary room temperatures.

5. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a tributyl borate, said borate being anhydrous and stable at ordinary room temperatures.

6. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid organic boron compound and an organic inert diluent, said compound and said diluent being anhydrous and stable at ordinary room temperatures.

'7. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aliphatic boron compound and an organic inert diluent, said compound and said diluent being anhydrous and stable at ordinary room temperatures.

8. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aromatic boron compound and an organic inert diluent, said compound and said diluent being anhydrous and stable at ordinary room temperatures.

9. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in an ester of boric acid and an organic inert diluent, said ester and said diluent being anhydrous and stable at ordinary room temperatures.

10. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a butyl borate and an organic inert diluent, said borate and said diluent being anhydrous and stable at ordinary room temperatures.

11. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid organic boron compound with the assistance of a soap of the group consisting of heavy metal soaps and naphthenic acid soaps, said compound and soap being anhydrous and stable at ordinary room temperatures.

12. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aliphatic boron compound with the assistance of a soap of the group consisting of heavy metal soaps and naphthenic acid soaps, said compound and soap being anhydrous and stable at ordinary room temperatures.

13. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid aromatic boron compound with the assistance of a soap of the group consisting of heavy metal soaps and naphthenic acid soaps, said compound and soap being anhydrous and stable at ordinary room temperatures.

14. An organosol comprising a finely dividedvitreous enamel frit uniformly dispersed in a liquid tributyl borate with the assistance of a soap of the group consisting of heavy metal soaps and naphthenic acid soaps, said compounds and said soap being anhydrous and stable at ordinary room temperatures.

15. An organosol comprising a finely divided vitreous enamel frit uniformly dispersed in a liquid ester of boric acid with the assistance of a soap of the group consisting of heavy metal soaps and naphthenic acid soaps, said compound and said soap being anhydrous and stable at ordinary room temperatures.

RUDOLPH S. BLEY. 

